We are away in our 2012 Swift Conqueror and all has been well for first week then yesterday the flush seemed to be staying on to long when pressed. Low and behold a little later it could be heard flushing when know one was even near the bathroom. Eventually after attempts to stop it, it emptied the tank but the motor could still be heard. We disconnected its power supply to circuit board after peeling off cover. Is the problem likely to be circuit board under push button or something elsewhere. Most problems I read are about flush not working. Any help would be appreciated.